It is conventional to supply a coolant/rinsing fluid, such as suds, to a tool and it is important to prevent that fluid from reaching the bearings. It also is conventional to supply lubricant to the bearings and it also is desirable to prevent that lubricant leaking externally. So one or more seals are interposed between the bearings and cutting tool. This creates problems.
It is usual to employ wiping seals which maintain contact between rotating and non-rotating parts even when the rotation ceases. The wiping seal has to be resiliently held in place. It is known to use so-called V -rings which comprise a ring to fit tightly on the spindle and an integral radial flange, made from a slightly resilient material such as a suitable plastic or rubber. However, the wiping creates friction, which leads to temperature increase and this can lead to inaccuracy in the machining operation because the spindle center positions will vary between cold and hot dimensions. Sometimes the shaft needs to be locally hardened or provided with for example ceramic surfaces as a seal component and to reduce wear and that also is expensive.
Labyrinth seals are often employed to avoid friction and its consequent heat and wear but multiple component labyrinths complicate the design, increase expense, and require additional length which is a disadvantage in many designs.
Another well known seal system employs radially extending flanges freely located so that liquid--lubricant or coolant--creeping along the spindle will reach the flange and be thrown off by centrifugal force into an annular collector space. But these, like labyrinth seals are primarily and sometimes exclusively useful when the spindle is in use. When stopped for any reason, undesired flow can occur from liquids already in place.
So the object of the .invention is to provide an improved and simplified design.